A distributed system structure for a large-way, symmetric multiprocessor
system using a bus-based cache-coherence protocol is provided. The
distributed system structure contains an address switch, multiple memory
subsystems, and multiple master devices organized into a set of nodes
supported by a node controller. The node controller receives commands from
a master device, communicates with a master device as another master
device or as a slave device, and queues commands received from a master
device. Due to pin limitations that may be caused by large buses,
functionality for address paths and data paths are implemented in the node
controller and are implemented in physically separate components. Commands
are sent from the node address controller to the node data controller to
control the flow of data through a node.